Mare Island marine weather forecast
Mare Island (USMI8) is a port in United States at 38°5.0′N 122°16.0′W. Today (Sep 16): S wind 10–11 kn, waves 1.7–2.1 m, from the NOAA GFS run 2026-09-16 18z. The live chart on this page shows current conditions and plans weather-optimized departures from this harbor.
Port facts (NGA World Port Index)| Position | 38°5.0′N 122°16.0′W |
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| UN/LOCODE | USMI8 |
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| Harbor size | Small |
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| Harbor type | Coastal natural harbor |
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| Shelter | Excellent |
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| Channel depth | 8 m |
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| Anchorage depth | 8 m |
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| Tide range | 1 m |
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| Pilotage | Compulsory |
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| Time zone | America/Los_Angeles |
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Facilities & services (NGA World Port Index)| Supplies | Fuel oil, diesel, water, provisions |
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| Repairs | Major (hull, machinery, electrical) |
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| Medical facilities | Available |
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10-day marine forecast — Mare Island
| Date | Wind | Gusts | Waves |
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| S 10–11 kn | 12 kn | 1.7–2.1 m |
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| SSE 5–14 kn | 21 kn | 1.4–1.7 m |
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| NNE 3–6 kn | 8 kn | 1.2–1.4 m |
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| S 4–7 kn | 9 kn | 1.3–1.6 m |
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| SSW 2–8 kn | 12 kn | 1.5–1.6 m |
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| SW 4–4 kn | 3 kn | 1.5–1.6 m |
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| NW 4–4 kn | 5 kn | 1.8–2.0 m |
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| SW 4–4 kn | 4 kn | 2.6–2.6 m |
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| NW 3–3 kn | 1 kn | 1.9–1.9 m |
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| S 8–8 kn | 9 kn | 1.2–1.2 m |
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Forecast from the NOAA GFS model run , waves from ECMWF WAM. Updated with each model cycle; the live chart below recalculates for your departure time and vessel.
What to watch in the forecast
Across the loaded 10-day outlook, the strongest daily modeled wind reaches 14 kn on Sep 17. The highest modeled significant wave height is 2.6 m on Sep 23. Compare the dated model run with official forecasts and warnings before departure.
Frequently asked
How is the weather at Mare Island right now?
As of the NOAA GFS run 2026-09-16 18z: S wind 10–11 kn, waves 1.7–2.1 m. The 10-day outlook is in the forecast table on this page and updates with each model cycle.
How big is the harbor at Mare Island?
Mare Island is classed as a small harbor (coastal natural harbor), with excellent shelter in the NGA World Port Index.
How deep is the approach to Mare Island?
Per the NGA World Port Index, the entrance channel carries about 8 m and anchorage depths run about 8 m. Verify against current official charts before entry.
What restricts entry to Mare Island?
Entry is affected by overhead clearance limits. Check the live forecast on this page and official notices before approach.